@dansup It depends on their business model. If they act like a responsible citizen of the fediverse, then I see no reason why I would block them.
Also, while it would be great if Meta allows the content on their platforms to break through their walled garden through ActivityPub, I don't see how they can make money off of that. If they start injecting ads in the feeds (which would be like Meta impersonating their users!) then that would warrant a block.